fix: Add a file size limit for settings file read

examples/demo.cpp

@@ -85,9 +85,9 @@ int main()
             json &manifest = manifest_store["manifests"][active_manifest];
 
             // scan the assertions for the training-mining assertion
-            string identifer = manifest["thumbnail"]["identifier"];
+            string identifier = manifest["thumbnail"]["identifier"];
 
-            reader.get_resource(identifer, thumbnail_path);
+            reader.get_resource(identifier, thumbnail_path);
 
             cout << "thumbnail written to " << thumbnail_path << endl;
         }

include/c2pa.hpp

@@ -738,7 +738,11 @@ namespace c2pa
 
         /// @brief Create a signer from a Signer pointer and take ownership of that pointer.
         /// @param c_signer The C2paSigner pointer (must be non-null).
-        Signer(C2paSigner *c_signer) : signer(c_signer) {}
+        Signer(C2paSigner *c_signer) : signer(c_signer) {
+            if (!c_signer) {
+                throw C2paException("Signer can not be null");
+            }
+        }
 
         /// @brief Create a Signer from signing credentials.
         /// @param alg Signing algorithm name (e.g., "ps256", "es256").

src/c2pa.cpp

@@ -496,6 +496,18 @@ inline std::vector<unsigned char> to_byte_vector(const unsigned char* data, int6
         }
 
         auto file = detail::open_file_binary<std::ifstream>(settings_path);
+
+        file->seekg(0, std::ios::end);
+        auto file_size = file->tellg();
+        file->seekg(0, std::ios::beg);
+        if (file_size < 0) {
+            throw C2paException("Settings file is not readable");
+        }
+        constexpr std::streamoff max_settings_size = 1024 * 1024; // 1 MB max, similar to c2pa-rs
+        if (file_size > max_settings_size) {
+            throw C2paException("Settings file is too large (>1MB)");
+        }
+
         std::string json_content((std::istreambuf_iterator<char>(*file)), std::istreambuf_iterator<char>());
 
         return with_json(json_content);
@@ -862,7 +874,11 @@ inline std::vector<unsigned char> to_byte_vector(const unsigned char* data, int6
     /// @brief  Get the size to reserve for a signature for this signer.
     uintptr_t Signer::reserve_size()
     {
-        return c2pa_signer_reserve_size(signer);
+        int64_t result = c2pa_signer_reserve_size(signer);
+        if (result < 0) {
+            throw C2paException();
+        }
+        return static_cast<uintptr_t>(result);
     }
 
     /// @brief  Builder class for creating a manifest implementation.